The present invention relates to an injector for medical treatment. More particularly, it relates to an injector filled with a pharmaceutical liquid, i.e. so-called "pre-filled syringe".
For the convenience of handling, there are widely used disposable injectors filled with a pharmaceutical these days. Particularly in the field of nuclear medicine, the use of such disposable injectors filled with a radiopharmaceutical liquid is favored to protect the operators such as physicians, nurses, etc. from radiation exposure.
A typical example of conventional injectors used for the purpose is shown in FIG. 1 of the accompanying drawings. However, such conventional injectors have certain drawbacks. For instance, a double-sided needle is used for the injectors so that whether the blood vessel is rightly secured with the needle can not be confirmed until the blood comes into the syringe (i.e. the cylinder). When a radiopharmaceutical liquid is to be administered, confirmation becomes more difficult, because the cylinder in such case is usually covered with lead or the like for prevention of radiation exposure While needles having various diameters, normally of 18 to 26 gauges, are to be used depending on age, administration site, etc., it is particularly difficult for ordinary hospitals to have a sufficient number and variety of such special needles as disposable double-sided needles